Trilobites Ride the Crazy Train

A new paper published recently in the journal Geology reports on peculiar conga party lines of our paleo-friend, the Trilobite. Gutierrez-Marco and colleagues discovered a quarry replete with marine invertebrate fossil, including potentially some of the largest trilobite specimens ever found. Curiously though, these capricious little critters were found exhibiting some rather gregarious behavior! They offer up 3 explanations: